Saturday, 8 December 2012

This post is
the first of a series of profiles about the scientists working on the TW:eed
project, so you can find out who they are and what they do. Our opening profile
is of Professor Jenny Clack FRS, the lead Principal Investigator for this
exciting multidisciplinary project.

Over the last
20 years Jenny has made major contributions to early tetrapod palaeontology,
especially in discovering, describing and analysing new and recently prepared
material from the Late Devonian and Early Carboniferous periods. Her work has
changed perceptions about the evolution of tetrapod organ systems (limbs,
breathing and hearing) and these concepts are now included in standard biology
text books.

Jenny is the
driving force behind the project. Determined to understand more about
terrestrial ecosystems and the acquisition of terrestrial capability by
tetrapods in 25 million years that followed the end Devonian mass extinction,
she assembled the team of scientists now working on TW:eed. In addition to her
research on these Early Carboniferous vertebrate fossils, Jenny is also in
charge of co-ordinating this four-year project.

Where do you work?

I am based at
the University of Cambridge and am Professor and Curator of Vertebrate
Palaeontology at the University Museum of Zoology, an integral part of the
Department of Zoology. I have several different strands to my work: curation,
teaching, research and some administration.

What inspired you to pursue a career
in vertebrate palaeontology?

I’ve been
interested in fossils and all aspects of natural history and sciences since
childhood, although fossils and palaeontology were a favourite. Thus I followed
a career in biology through school and university. After my first degree,
although I would have liked to work on a PhD in vertebrate palaeontology,
opportunities were not available. Instead, I entered the museum world, via
holiday work, a Museum Studies degree and then a spell of 7 years in Birmingham
Museums and Art Gallery. At that time, they had a Natural History department
and a Museum Education department, and I worked spells in both. (Both are now gone.)
During the latter spell, I was given the chance to renew my attempt to enter
the field of palaeontology by returning to my first university for a PhD.

What would be an ideal working day?

Discovering
new fossils, thinking about and examining fossil material that I or others have
prepared, microscope work and illustrating specimens. Then writing them up for
publication, which I don’t usually find a chore, but actually enjoy doing.

What do you think are the key
character traits needed to be a successful palaeontologist?

It depends on
what kind of palaeontologist you are. Many aspects of the field are now
computer-based, but for my kind, who are interested in the actual materials and
the animals they represent, an ability to think in three dimensions, to
visualise anatomy, to interpret mashed-up fossils. You sometimes have to turn
your first thoughts on their head (not literally) and not be constrained by
received ideas.

Do you have favourite fossil from all
those that you have studied?

Probably the
one I did my PhD on, if I have to choose. It’s a Coal Measures tetrapod called Pholiderpeton and it belongs to a group
called anthracosaurs. It’s quite a big beast, one you might describe as
road-kill except that the bones are well preserved if disarticulated. It
provided new insight and thoughts about several previously unknown aspects of
anthracosaur anatomy. In effect, it launched my career. Maybe that’s why the
Romer’s Gap project is so appealing – it’s back to the Carboniferous for me.

What was your inspiration for setting
up the TW:eed project?

The knowledge
that my colleagues Tim Smithson and the late Stan Wood had found numerous
fossils from a previously almost blank period for fossils lasting about 20
million years and covering the time period during which terrestrial tetrapods
and modern-aspect ecosystems were becoming established. If I had been asked
what I most wished for in the closing years of my career that would have been
my answer. The project then grew and grew, and it was quite difficult not to
take on too much.

What are the major scientific
challenges in vertebrate palaeontology?

Although many
of my junior colleagues have recently been appointed to academic positions,
funding long-term will be a problem. However, more fossil material is being
discovered all over the world and brilliant new techniques are helping to
formulate new ideas and questions. Linking these to evolutionary developmental
genetics will play a larger part in our activities, and looking at animals’
morphology, growth trajectories, biomechanical potential and palaeoecology in
more sophisticated ways will be other growth areas.

When you aren’t thinking about
vertebrate palaeontology, what do you like to do?

Singing. My
husband and I sing in two choirs which together take up a lot of our time
outside work. We also spend a lot of time gardening.

In this short
post I will continue to explain the process of rock crushing. The final stage
is to take the millimetre size rock pieces and to crush them up into micron
size pieces, a process called milling. We use a machine called a Planetary
Mill, which you can see in the photo below. There are four receptacles with
balls inside that spin round and crush the rock into small grains. The result
is a fine rock powder, which feels quite like flour. We use this rock powder
for various geochemical analyses such as determining the carbon isotopic
composition of the rock.

For my rock
samples this is a fairly quick process, as sedimentary rocks are not very hard
compared to igneous and metamorphic rocks. However, a lot of time has to be
spent on cleaning the receptacles and machine between each batch, to avoid
contamination.

Top: The Planetary Mill. Bottom left: one
receptacle containing rock pieces and balls to crush the rock. Bottom right: the
resulting powder produced by milling.

Wow! Of the week

When I found this
rock while sawing last week, it was a total wow! moment. As before, with other
wow! specimens, on the outside the rock looked very non-descript, just a sandy
lump. But once I sawed into the rock I saw all these holes throughout the rock
that I haven’t seen before. I tested to rock with some dilute acid and
discovered that calcite exists in the holes, while the rest of the rock is made
from sand. I think that these holes were formed by gypsum crystals that have
now dissolved, as some of the holes are long and thin like the crystal habit of
gypsum.

This is the
first direct evidence I have found of gypsum from the site I am working on. Its
very exciting as it means that this rock formed from the evaporation of water,
maybe in a lagoon that dried up. And it might indicate that seawater inundated
the area prior to its drying out. In the bigger picture, its one more piece in
the puzzle of understanding the environment the tetrapods lived in, fantastic!